Answer:Any of these speakers should work well with the SR6007, which is specified to output 110 watts per channel into 8 ohms (2 channels driven from 20Hz to 20kHz) with 0.08% THD (total harmonic distortion). Into 6 ohms, the power output is specified to be 190W, but that's with 10% THD using a 1kHz test tone, not the entire audible range.

The Klipsch, KEF, JBL, and Tannoy speakers you list are spec'd with a nominal impedance of 8 ohms. The Monitor Audio and Dali models are 6 ohms, and the Heco is specified as "4-8 ohm," which probably means that the impedance varies from 4 to 8 ohms depending on the frequency. In fact, the impedance of all speakers varies with frequency, but few companies specify the range. In any event, the SR6007 should have no trouble driving any of them, though I would probably stick with the 8-ohm models just so the amp doesn't have to work as hard as it would with 6-ohm speakers.

In terms of maximum continuous power handling, they're all in the ballpark, ranging from 125W for the Monitor Audio Silver RX6 to 200W for the KEF iQ90 and JBL Studio 190. Yes, they can all handle more power than the Marantz can provide—at least into 8 ohms—but under most circumstances, you'll only be using a few watts anyway.

How loud they will play with those few watts is determined by their sensitivity, which is defined as the sound pressure level produced by 1 watt of power as measured at a distance of 1 meter. The highest sensitivity of the bunch is the Klipsch RF 82-II at 98dB—no doubt due in part to its horn-loaded tweeter—while the lowest is the KEF Q500 at 87dB. The rest are between 89 and 91dB, though the sensitivity of the Heco is not specified as far as I could find.

As I said earlier, I would probably limit my choices to the 8-ohm models, which include the Klipsch RF 82-II, KEF Q500 and iQ90, JBL Studio 190, and Tannoy Revolution DC6T (shown above with center, surrounds, and subwoofer in a complete home-theater system along with the Marantz SR6007). This will put less burden on the SR6007's amp and keep the distortion down as well.

So which one should you get? I can't answer that question, because it depends greatly on your personal taste; each model has its own sonic signature that is appealing to some but not to others. If possible, try to audition them to see which one sounds best to you. Also, read reviews from trusted sources, which often provide measurements that will confirm or belie the manufacturer's specs. You can find our review of the KEF iQ90 here and the Tannoy Revolution DC6T here.